Improved ventilation by CFD prediction of thermal conditions among pigs

TY - ABST

T1 - Improved ventilation by CFD prediction of thermal conditions among pigs

AU - Bjerg, Bjarne Schmidt

PY - 2018

Y1 - 2018

N2 - Negative pressure ventilation with diffuse air inlet through a layer of mineral wool in the ceiling is the dominant ventilations method in Danish pig production. The method constitutes a simple way to generate appropriate thermal conditions among the animals, especially in periods with relatively low outdoor temperatures. To improve the chilling of animals in warmer periods newer finisher pig units are often equipped with an additional ceiling air inlet above each pen. These inlets directs a concentrated air jet directly down in the animal occupied zone, and are usually closed at outdoor temperatures below around 20 ºC, and fully open at higher outdoor temperatures. Earlier research indicated that negative consequences of high temperature may occur at significant lower outdoor temperature than 20 ºC if the sole air intake is through the porous material in the ceiling. The problem is most evident in pigpens with solid floor in the lying area, where warm conditions increases the risk of fouling the pen floor, and may cause impaired pen hygiene and air quality as well as increased emissions and workload. To investigate options to provide suitable thermal condition at outdoor temperatures between 10 and 20 ºC the earlier research included CFD to predict the effect of a gradually adjustment of the ceiling inlet opening depending of the outdoor temperature. The results indicated that it might be possible to design and locate a ceiling inlet where the opening flap are controlled in a way where the effective temperature among the pigs is maintained at a desired level at outdoor temperatures up to around 19 ºC. The study also indicated that an air jet attached to the ceiling, deflected by a back wall and continued attached to the back wall down in the animal occupied zone was more effective to chill the animals than a free jet directly from the inlet to the animal occupied zone. This result led to the hypothesis that it would be more effective to move the inlet closer to the back wall so the distance from the inlet becomes shorter, and so the inlet could be more open before the jet changed from an attached jet to a free jet. In this research, results obtained by a new CFD model confirmed the mentioned hypothesis, and indicated that the effective temperature among the pigs can be maintained at a desired level at outdoor temperatures up to around 22 ºC.

AB - Negative pressure ventilation with diffuse air inlet through a layer of mineral wool in the ceiling is the dominant ventilations method in Danish pig production. The method constitutes a simple way to generate appropriate thermal conditions among the animals, especially in periods with relatively low outdoor temperatures. To improve the chilling of animals in warmer periods newer finisher pig units are often equipped with an additional ceiling air inlet above each pen. These inlets directs a concentrated air jet directly down in the animal occupied zone, and are usually closed at outdoor temperatures below around 20 ºC, and fully open at higher outdoor temperatures. Earlier research indicated that negative consequences of high temperature may occur at significant lower outdoor temperature than 20 ºC if the sole air intake is through the porous material in the ceiling. The problem is most evident in pigpens with solid floor in the lying area, where warm conditions increases the risk of fouling the pen floor, and may cause impaired pen hygiene and air quality as well as increased emissions and workload. To investigate options to provide suitable thermal condition at outdoor temperatures between 10 and 20 ºC the earlier research included CFD to predict the effect of a gradually adjustment of the ceiling inlet opening depending of the outdoor temperature. The results indicated that it might be possible to design and locate a ceiling inlet where the opening flap are controlled in a way where the effective temperature among the pigs is maintained at a desired level at outdoor temperatures up to around 19 ºC. The study also indicated that an air jet attached to the ceiling, deflected by a back wall and continued attached to the back wall down in the animal occupied zone was more effective to chill the animals than a free jet directly from the inlet to the animal occupied zone. This result led to the hypothesis that it would be more effective to move the inlet closer to the back wall so the distance from the inlet becomes shorter, and so the inlet could be more open before the jet changed from an attached jet to a free jet. In this research, results obtained by a new CFD model confirmed the mentioned hypothesis, and indicated that the effective temperature among the pigs can be maintained at a desired level at outdoor temperatures up to around 22 ºC.

M3 - Conference abstract for conference

T2 - the XIX. World Congress of the International Commission of Agriculture and Biosystems Engineering (CIGR)

Y2 - 22 April 2018 through 25 July 2018

ER -